Installing

Quick start

The following is an example of a msmtp configuration file for several accounts. If msmtp throws errors when using this file, search for double byte '\xc2\xa0' characters that may have been erroneously inserted.

Do not merely use "echo 'Yadda, yadda, yadda.'" instead of "cat test.mail". This causes at least Gmail and Yahoo to deliver the mail incorrectly.

Configuring cron for msmtp

Assuming you're using the default {cron} daemon, cronie, you'll want to make sure it knows to use msmtp rather than sendmail.

You can do this by adding the proper crond option in /etc/conf.d/crond:

CRONDARGS=-m/usr/bin/msmtp

Miscellaneous

Practical password management

The password directive may be omitted. In that case, if the account in question has auth set to a legitimate value other than off, invoking msmtp from an interactive shell will ask for the password before sending mail. msmtp will not prompt if it has been called by another type of application, such as Mutt.
There is a solution for such cases: the --passwordeval parameter.
You can call msmtp to use an external keyring tool like gpg:

msmtp --passwordeval 'gpg -d mypwfile.gpg'

If gpg prompt for the passphrase cannot be issued (e.g. when called from Mutt) then start the gpg-agent before.

Note: As of 2012-07-06 the version in the official Arch Linux repositories is broken: any call to this parameter will result in a segmentation fault. This bug has been fixed upstream, so you can use msmtp-gitAUR from the AUR.

If you cannot use a keyring tool for any reason, you man want to use the password directly. There is a patched version msmtp-pwpatchedAUR in the AUR that provides the --password parameter. Note that it is a huge security flaw, since any user connected to you machine can see the parameter of any command (in the /proc filesystem for example).

If this is not desired, an alternative is to place passwords in ~/.netrc, a file that can act as a common pool for msmtp, OfflineIMAP, and associated tools.

Using msmtp offline

Although msmtp is great, it requires that you be online to use it. This isn't ideal for people on laptops with intermittent connections to the Internet or dialup users. Several scripts have been written to remedy this fact, collectively called msmtpqueue.

The scripts are installed under /usr/share/doc/msmtp/msmtpqueue. You might want to copy the scripts to a convenient location on your computer, (/usr/local/bin is a good choice).

Finally, change your MUA to use msmtp-enqueue.sh instead of msmtp when sending e-mail. By default, queued messages will be stored in ~/.msmtpqueue. To change this location, change the QUEUEDIR=$HOME/.msmtpqueue line in the scripts (or delete the line, and export the QUEUEDIR variable in .bash_profile like so: export QUEUEDIR="$XDG_DATA_HOME/msmtpqueue").

When you want to send any mail that you've created and queued up run:

$ /usr/local/bin/msmtp-runqueue.sh

Adding /usr/local/bin to your PATH can save you some keystrokes if you're doing it manually. The README file that comes with the scripts has some handy information, reading it is recommended.

Vim syntax highlighting

The msmtp source distribution includes a msmtprc highlighting script for Vim. Install it from ./scripts/vim/msmtp.vim.

Send mail with PHP using msmtp

Look for sendmail_path option in your php.ini and edit like this:

sendmail_path = "/usr/bin/msmtp -C /path/to/your/config -t"

Note that you can not use a user configuration file (ie: one under ~/) if you plan on using msmtp as a sendmail replacement with php or something similar.
In that case just create /etc/msmtprc, and remove your user configuration (or not if you plan on using it for something else). Also make sure it's readable by whatever you're using it with (php, django, etc...)

From the msmtp manual: Accounts defined in the user configuration file override accounts from the system configuration file. The user configuration file must have no more permissions than user read/write

So it's impossible to have a conf file under ~/ and have it still be readable by the php user.

To test it place this file in your php enabled server or using php-cli.

Troubleshooting

Issues with TLS

Just follow the fine manual. It explains you how to find out the server certificate issuer of a given smtp server. Then you can explore the /usr/share/ca-certificates/ directory to find out if by any chance, the certificate you need is there. If not, you will have to get the certificate on your own.

If you are trying to send mail through GMail and are receiving this error, have a look at this thread or just use the second GMail example above.

If you are completely desperate, but are 100% sure you are communicating with the right server, you can always temporarily disable the cert check: